With the development of technologies, functions of a mobile terminal such as a mobile phone are increasingly powerful. Software (also known as firmware) in the mobile terminal also grows in size. Once a mobile terminal is launched to the market and its firmware needs to be upgraded, because users are widely distributed, a traditional upgrade method, such as a recall of mobile terminals by a manufacturer for upgrade or an upgrade through the Internet, is hardly feasible.
Therefore, a technology of upgrading the firmware of a mobile terminal by using a FOTA technology is applied. FOTA sends an upgrade packet to the mobile terminal through an air interface of the mobile terminal for the mobile terminal to upgrade the firmware, such as a code and file system, on its own. Because the operation is simple and may be completed by a user itself, a FOTA upgrade method is more and more preferred by a carrier.
A common existing FOTA upgrade method is to, by using a certain algorithm, calculate an upgrade packet for two versions of a certain firmware before and after an upgrade, download the upgrade packet through the air interface of the mobile terminal to the mobile terminal of a user, start a FOTA upgrade process in the mobile terminal and complete the upgrade of the firmware, and restart the mobile terminal to start the firmware after the upgrade.
During implementation of the present invention, the inventor finds that the prior art at least has the following problem: The upgrade packet for firmware upgrade is directly transmitted to the mobile terminal through the air interface, bringing the mobile terminal under a threat of intrusion by illegal codes.